The first thing you need to know is that MicroSoft Teams and VS Code are all completely owned by JS.Development(more precisely, Electron supported TypeScript).

Second, Office 365 has a lot of UI elements. A large part of it is based on React Native, but APIs and services are written in C++, C#, and so on. Sean emphasized that he maintains a lot of respect for traditional programming languages, so Office 365 is not entirely rewritten with JavaScript/TypeScript.

Finally, as one of the traders of the Edge browser, he emphasized that the EdgeHTML engine is entirely written in C++, butMicrosoftAlso allowed to run JavaScript (compiled by TypeScript) in development tools.

In other words, word can't be completely written in JS after all, but in the open cross-platform world in the future, many new programs or products that need to be reinvented will seem to be declining in the number of JS camps.